Metal cleaning



Patented May 21, '1929.

UNITED STATES v 1,713,653 PATENT OFFICE.-

JAMES H. GRAVELL, OF ELKINS PARK, PENNSYLVANIA, ASSIGNOB TO AMERICAN CHEMICAL PAINT COMPANY, OF AMBLEB, PENNSYLVANIA, A CORPORATION O DELAWARE.

METAL CLEANING.

No Drawing.

This invention relates to the art of cleaning ferrous metals and although generally useful in that art, it is particularly directed to preparing steel for painting. 7

Steel is prepared for painting by treating it with an admixture of a metal etching acid anda material. for causing the acid to wet even an oily surface, an admixture of alcohol and phos horic acid is a typical example. After t e cleaner has performed its function it is removed along with the productsof its reaction by washing the surface with water. The surface is then dried or is permitted to dry, and is then ready for receiving the priming coat of the protective coating which may be paint, varnish, lacquer or japan, and the like.

It is,found that afterthe drying operation, the metal is stained due to the formation of iron oxide which not only mars the surface but acts to prevent the priming coat or protective coating from contacting with the true metallic surface.

One object of the invention is to provide a method of cleaning steel which reduces or obviates the staining of the workto such an extent that it becomes commercially negligible. Further objects of this invention are to provide a cleaning method that will not cause rust; a cleaning method that will permit the 'cleaned'metal to remain for long periods without a subsequent protective coating and without rusting; a cleaning. method which simultaneously cleans and provides a protective coating. It is also an object of this invention to provide a cleaner for steel whose use will not cause the metal to rust or tarnish. c

I have discovered that if steel is metallically plated while it is being cleaned, staining in the washing step of the cleaning process is avoided. I have found that arsenic is best suited for my purpose, as a very thin coating or film of it sufiices for my purpose, and under proper conditions it dissolves readily in suitable acid admixtures, and in addition it is electro negative to steel, and hence plates out of solution by simple immersion or contact and therefore does not require recourse to the aid of an electric current.

Though I may dissolve arsenic in the form 'of arsemous oxide directly in my acid admixture, I prefer to first dissolve the arsenious oxide in" an alkaline solution and then to introduce the proper amount of this alkaline Application filed June 22,

. arsenic may be made by hand marks, acid runs,

1928. Serial No. 117,876.

solution into my admixture, as by this method the solution of the arsenic in my admixture is more rapid. A suitable alkaline solution of mixing:

Water l .92 gallons- Sodmm hydroxide 1.33 pounds Arsenious oxide 1.66 poundsalcohol, ethyl alcohol, denatured alcohol,

butyl alcohol, propyl alcohol, amyl alcohol, acetone, ethyl acetate, methyl-ethyl-ketone, fusel oil and the like. I consider tliat..denatured alcohol either alone or mixed with butyl alcohol produces the best results.

A suitable admixture for vention is made by using:

Water .50 Phosphoric acid (85%) .33 Denatured alcohol .20 Butyl alcohol .0'5 Alkaline arsenic solution .02

The metal to be treated according to my method may be befouled by rust, oil, dirt, soldering fluid or any of those objectionable materials which are apt to cause a development of defects in applied finishes. When manipulated according to my process, m'y cleaner removes these ob jectionable'materials and leaves the cleaned surface free from tarnish and in a suitable condition for receiving the protective coatin r o carry out the process, I apply the de-. scribed admixture to the metal to becleaned in any suitable manner, but preferably with a brush; I allow the admixture sufiicient time to act on the surface, assisting the action in the meantime if necessary by scrubbing with an abrasive; when the proper degree of cleanliness has been obtained, the spent cleaner along with the deleterious productsof its reaction are removed This removing step in the process is best accomplished by washin the metal with water. The water may be either cold or hot but-preferably first cold and then hot, thus leaving the metal heated practicing my in- Gallons. I

and causing it to dry quickly, by evaporation. The dryin may be assisted by wiping -with cloths or b owin ofi with a jet of air.

The action 0 my cleaner is such that a thin coating or film of metallic arsenic is deposited on the cleaned metal which acts to prevent the formation of tarnish during the adapted to remove oil from an oily surface in proportions fixed by the fact that the more acid the quicker the removal of oxide and the more of the material the better the removal the solution and adapted ,lic arsenic on ofoil and a compound of arsenic in proportion fixed by the possibility of getting it into y contact to plate out afilm of metallic arsenic on the ferrous metal surface. Y

2. A cleaner for ferrous metals comprising an admixtureof metal etching acid and a material adapted toremove oil from an oily surface in proportions" substantially as described, and a compound of arsenic in substantially the proportion described and adapted by contact to deposit a film of metal- Ithie ferrops metal which film o oses tarnis urin r 'n Pp JAMIS l l GRAVELL. 

